The present invention relates generally to an improved pneumatic spreader system for distribution of agricultural crop treating chemicals in granular, particulate or pulverulent solid form upon the soil, and more particularly to a system for achieving such distribution through the use of a plurality of elongated delivery tubes or booms with discharge orifices arranged adjacent the outer tips thereof, and wherein shut-off means are provided for individual booms so as to interrupt flow of particulate or granular material from certain specific selected booms, while the other booms are permitted to remain active and in normal operation. The apparatus of the present invention is effective against granular material build-up or clogging, and is adapted to produce a more uniform distribution of solids at a constant application rate through those booms remaining active.
Pressurized pneumatic systems utilizing a single distribution head delivering or metering a supply of granular or particulate material for controlled discharge of such material from a plurality of elongated booms have been employed in the past, however the systems currently in use normally deliver granular products through all of the booms at all of the time. Reliable and non-clogging means capable of providing uniform distribution and application rates have not been available for those systems providing for periodic and controlled interruption of delivery of granular products or materials from certain selected booms. The present invention provides a reliable and non-clogging system for such controlled distribution, while at the same time maintaining the distribution and application rate at a substantially uniform and constant level through the active booms.
Agricultural techniques require the utilization of soil treating agents to either encourage, discourage, destroy, or inhibit plant growth. Such agents may generally be characterized as crop treating chemicals, and include materials designated as nutrients such as fertilizers, and pesticides such as insecticides and herbicides including pre-emergent and/or post-emergent plant growth inhibitors. Accordingly, the term "crop treating chemical" is used in a comprehensive sense to incorporate those various ingredients utilized in agriculture to treat either the soil, the growing crop or plants, or certain insects which may damage the crop. Active materials used for treatment are commonly found in one of three forms, either water soluble, water wettable, particulate solid or in surface-impregnated solid form. In connection with the present invention, granular materials and/or surface-impregnated (wetted) granular materials are of particular interest, with the system of the present invention being particularly adapted for use in connection with the selective and uniform distribution of such materials through the system and onto the soil or other surfaces being treated.
In the treatment of agricultural fields and crops through spreading of one or more active treating ingredients, the efficiency of the treatment operation may be enhanced if the distribution of the ingredients is maintained at a uniform and/or controllable rate. Uniform application rates have become an important factor, particularly with the use of certain pesticides and/or herbicides which require a predetermined application rate in order to be effective, and yet not harmful to the crop being treated. Additionally, the efficiency of the operation may be enhanced if the actual load required to be carried by the spreading equipment is reduced. Therefore, the utilization of dry particulate solids will substantially reduce the load requirement, inasmuch as water or other treatment medium or treatment vehicle is not required. The need for multiple passes may be reduced if surface-impregnated granular material may be uniformly spread, such as through the use of a granular fertilizer having a surface impregnated with a particular pesticide. The utilization of pressurized pneumatic systems will normally eliminate or substantially reduce the vehicle load by eliminating the need for large quantities of water, since pneumatic systems normally utilize a compressor to generate a supply of compressed air in lieu of a liquid plus liquid pressure source as a means to create a medium for accomplishing delivery of the treating ingredient onto the soil.
Pneumatic spreader systems typically are mounted upon self-propelled vehicles, thereby providing a means for achieving the distribution. In order to render these systems efficient, elongated booms are employed, and it is not uncommon for such booms to extend outwardly a distance of 18 feet or more from the center axis of the vehicle. Frequently, when the operator is close to the edge of a field, the entire width-spreading capability of the system is not needed, and in fact any double-coverage may be both wasteful and possibly damaging to the crop being treated. Accordingly, and in order to achieve both a wide expanse spreading capability, as well as the capability of selectively reducing the width, the system of the present invention permits periodic interruption of flow or delivery of particulate material from certain selected booms. In order to render the system more highly advantageous, this interruption of flow is achieved while maintaining uniform application rates and without increasing the tendency of the system to become clogged. An added advantage of the system permits intermittent shut-down of certain booms when the fertility index varies across the field being treated. In such instances, it may become desirable to eliminate application of certain materials in certain pre-defined areas across a given field, thus providing greater versatility for the apparatus of the present invention.
In order to maintain normal flow of particulate solids through a pressurized pneumatic system, uniform, consistent and uninterrupted flow patterns are desirable. However, such application rate consistency becomes difficult, if not impossible to achieve, when attempts are made to periodically block-off the flow of particulate solids to selected booms. Such attempts frequently create a non-uniformity in application rates and normally lead to a tendency of the particulate solids or granular materials, particularly surface treated granular materials, to clog portions of the distribution system, and thereby establish a need for temporary shut-down of the equipment until the boom may be cleared and thus relieve the clogging.
As indicated, uniformity of distribution of particulate materials depends to a certain extent upon predetermined patterns of air movement through the entire system, including the distribution head, the material transferring conduits, as well as the individual booms. Attempts to simply block-off the flow of air through one or more booms may interfere with normal and anticipated patterns through the system. Furthermore, attempts to modify the position of individual material transferring conduits throughout the system contributes to interference with normal patterns of flow through the system, and thus leads to lack of uniformity of distribution of particulate materials. As indicated, pressurized pneumatic systems normally employ a plurality of elongated hollow delivery booms, with these booms extending outwardly of the vehicle to certain predetermined and differing lengths. In order to preserve operational integrity and predictability, therefore, uniformity of patterns of air movement, including uniformity of flow volumes through individual booms comprising the entire system is a desirable objective and goal. The features of the present invention permit selective shut-off of flow of granular material through certain preselected booms, it having been found that the system accomplishes this goal without increasing the tendency to clog, and thus preserving uniformity of continued distribution of particulate solids from the remaining operative booms in the system. The features of the present invention have been found desirable for improving the performance of systems utilizing elongated hollow discharge or delivery booms through selective shut-off of certain predetermined booms, whenever it is desired that the system operate with certain selected booms being non-functional.